AWS F4.1:2017

An American National Standard

Safe Practices for the Preparation of Containers and Piping for Welding, Cutting, and Allied Processes

AWS F4.1:2017

An American National Standard

Approved by American National Standards Institute

August 3, 2017

Safe Practices for the Preparation of Containers and Piping for Welding, Cutting, and Allied Processes

6th Edition

Supersedes AWS F4.1:2007

Prepared by the AWS Committee on Labeling and Safe Practices

Under the Direction of the AWS Committee on Safety and Health

Approved by the AWS Board of Directors

Abstract

This standard informs the reader of the necessary safe practices to be followed in the cleaning and preparation of con- tainers and piping for welding or cutting. It describes various methods for cleaning, including water, steam, hot chemical and mechanical, and techniques to be used for their proper preparation, such as inerting.

ISBN: 978-0-87171-923-2

© 2017 by American Welding Society

All rights reserved Printed in the United States of America

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Statement on the Use of American Welding Society Standards

All standards (codes, specifications, recommended practices, methods, classifications, and guides) of the American Welding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of the American National Standards Institute (ANSI). When AWS American National Standards are either incorporated in, or made part of, documents that are included in federal or state laws and regulations, or the regulations of other governmental bodies, their provisions carry the full legal authority of the statute. In such cases, any changes in those AWS standards must be approved by the governmental body having statutory jurisdiction before they can become a part of those laws and regulations. In all cases, these standards carry the full legal authority of the contract or other document that invokes the AWS standards. Where this contractual relationship exists, changes in or deviations from requirements of an AWS standard must be by agreement between the contracting parties.

AWS American National Standards are developed through a consensus standards development process that brings together volunteers representing varied viewpoints and interests to achieve consensus. While AWS administers the process and establishes rules to promote fairness in the development of consensus, it does not independently test, evaluate, or verify the accuracy of any information or the soundness of any judgments contained in its standards.

AWS disclaims liability for any injury to persons or to property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance on this standard. AWS also makes no guarantee or warranty as to the accuracy or completeness of any information published herein.

In issuing and making this standard available, AWS is neither undertaking to render professional or other services for or on behalf of any person or entity, nor is AWS undertaking to perform any duty owed by any person or entity to someone else. Anyone using these documents should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. It is assumed that the use of this standard and its provisions is entrusted to appropriately qualified and competent personnel.

This standard may be superseded by new editions. This standard may also be corrected through publication of amendments or errata, or supplemented by publication of addenda. Information on the latest editions of AWS standards including amendments, errata, and addenda is posted on the AWS web page (www.aws.org). Users should ensure that they have the latest edition, amendments, errata, and addenda.

Publication of this standard does not authorize infringement of any patent or trade name. Users of this standard accept any and all liabilities for infringement of any patent or trade name items. AWS disclaims liability for the infringement of any patent or product trade name resulting from the use of this standard.

AWS does not monitor, police, or enforce compliance with this standard, nor does it have the power to do so.

Official interpretations of any of the technical requirements of this standard may only be obtained by sending a request, in writing, to the appropriate technical committee. Such requests should be addressed to the American Welding Society, Attention: Managing Director, Standards Development, 8669 NW 36 St, # 130, Miami, FL 33166 (see Annex B). With regard to technical inquiries made concerning AWS standards, oral opinions on AWS standards may be rendered. These opinions are offered solely as a convenience to users of this standard, and they do not constitute professional advice. Such opinions represent only the personal opinions of the particular individuals giving them. These individuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or interpretations of AWS. In addition, oral opinions are informal and should not be used as a substitute for an official interpretation.

This standard is subject to revision at any time by the AWS Committee on Safety and Health. It must be reviewed every five years, and if not revised, it must be either reaffirmed or withdrawn. Comments (recommendations, additions, or dele- tions) and any pertinent data that may be of use in improving this standard are required and should be addressed to AWS Headquarters. Such comments will receive careful consideration by the AWS Committee on Safety and Health and the author of the comments will be informed of the Committee’s response to the comments. Guests are invited to attend all meetings of the AWS Committee on Safety and Health to express their comments verbally. Procedures for appeal of an adverse decision concerning all such comments are provided in the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained from the American Welding Society, 8669 NW 36 St, # 130, Miami, FL 33166.

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Personnel

AWS Safety and Health Committee

D. E. Clark, Chair Consultant

D. Werba, Vice Chair Miller Electric Manufacturing Company

1. P. Hedrick, Secretary American Welding Society

   S. R. Fiore Hobart Brothers Company

   S. L. Foxworth ESAB Welding and Cutting Products

   M. Haaksma Orange County Ironworks, LLC

   K. A. Lyttle Consultant

   A. F. Manz A. F. Manz Associates

   1. M. Merlo-Joseph Apeks Supercritical

      J. Petkovsek The Lincoln Electric Company

      1. M Santasiero NJCTTC

      2. Solomon Extruflex North America

         
         

         Advisors to the Safety and Health Committee

      3. M. Donovan Sheet Metal Workers Local #265

         S. E. Ferree Consultant

         D. A. Fink The Lincoln Electric Company

         1. G. Harvey Hobart Brothers Company

            1. Hudson Hobart Brothers Company

J. D. Jennings Expert Services

T. Lyon Consultant

D. H. Sliney Consultant

1. J. Tucker Consultant

   
   

   AWS Subcommittee on Labeling and Safe Practices

   A. F. Manz, Chair A. F. Manz Associates

   D. Werba, Vice Chair Miller Electric Manufacturing Company

2. P. Hedrick, Secretary American Welding Society

D. N. Dunbar The Lincoln Electric Company

D. A. Fink The Lincoln Electric Company

J. L. Hege Manitowoc—Shady Grove

Advisors to the AWS Subcommittee on Labeling and Safe Practices

B. Berg Navy and Marine Corps Public Health

S. E. Ferree Consultant

J. D. Jennings Expert Services

L. E. Montville NFPA

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Foreword

This foreword is not part of this standard but is included for informational purposes only.

In 1940, the AWS Committee on Safety Recommendations published Recommended Procedure to Be Followed in Pre- paring for Welding or Cutting Certain Types of Containers which have Held Combustibles. The document was updated in 1952 and 1965. Based on this earlier document, the first edition of AWS F4.1 was published in 1980 with subsequent revisions in 1988, 1994, 1999, and 2007. This revision is the sixth edition of AWS F4.1. Changes from the fifth edition include: The title was changed from “Safe Practices for the Preparation of Containers and Piping for Welding and Cut- ting” to “Safe Practices for the Preparation of Containers and Piping for Welding, Cutting, and Allied Processes.” Safety information was added to the Scope and references were updated. Changes in text are indicated by a vertical margin line.

This document addresses one of the leading causes of accidents among welders and cutters, that is, work on closed containers where previous contents are unknown. It provides the safety precautions necessary for prevention of such accidents, and the techniques used for preparation of containers, including piping, and represents current practice in various segments of U.S. industry.

Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary, Safety and Health Committee, American Welding Society, 8669 NW 36 St, # 130, Miami, FL 33166.

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Table of Contents

Page No.

Personnel v

Foreword vii

1. Introduction and Scope 1

   1. Introduction 1

   2. Scope 1

   3. Safety 1

2. Referenced Documents 2

3. Terms and Definitions 2

4. Preparing the Container for Cleaning 2

   1. Determination of Hazardous Characteristics of Contents 2

   2. Unknown Substances 3

   3. Designation of Cleaning Procedure 3

   4. Cleaning Containers 3

   5. Other Precautions 3

5. Methods of Cleaning and Guidelines for Selection 3

   1. Water Cleaning 3

   2. Hot Chemical Solution Cleaning 3

   3. Steam Cleaning 4

   4. Mechanical Cleaning 4

   5. Chemical Cleaning 4

   6. Combination of Methods 4

6. Preparation for Welding and Cutting 4

   1. Guidelines 4

   2. Safe Practices 4

Annex A (Informative)—Bibliography 7

Annex B (Informative)—Requesting an Official Interpretation on an AWS Standard 9

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Safe Practices for the Preparation of Containers and Piping for Welding, Cutting, and Allied Processes

1. Introduction and Scope

   1. Introduction. Explosions, fires, and health hazards may result if welding, cutting, heat, friction, impact, or other hot work is applied on containers that are not free of hazardous substances, such as combustible, reactive, or toxic solids, liquids, vapors, dusts, and gases. No container shall be presumed to be clean or safe, but containers can be made safe for work, provided the safe practices prescribed herein or their equivalent are followed.

   2. Scope. These safe practices shall apply to the preparation for welding or cutting of metal containers and piping. For the purposes of this document, references to precautions for welding or cutting are also intended to apply to all metal working operations (i.e., brazing, grinding, soldering, thawing pipes, using heat guns, using spark-producing power tools, straightening, thermal spraying) involving heat. Cleaning of used containers is necessary in all cases before weld- ing or cutting. The term container, as used herein, includes piping.

      The safe practices presented here are not intended to replace either regulatory standards or more stringent practices of industries that have expert knowledge of handling hazardous substances. Even a water tank should be considered haz- ardous unless a qualified person has declared it safe to weld or cut. Consequently, safe practices presented here are not intended to apply to the following:1

      1. Containers and confined spaces that can be entered by workers (see ANSI Z117.1, Safety Requirements for Con- fined Spaces).

      2. Containers that have contained radioactive substances

      3. Compressed gas containers

      4. Containers that have held explosive substances (such as nitrocellulose, pyroxylin solution, etc.)

      5. Tanks, bunkers, or compartments on ships

      6. Gasometers or gas holders for natural and manufactured gases

      7. Outside, above-ground, petroleum storage tanks

      8. Containers holding flammables that are to be repaired while in service

   3. Safety. Safety and health issues and concerns are addressed in this standard. Safety and health information is available from the following sources: American Welding Society:

      1. ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes

      2. AWS Safety and Health Fact Sheets

      3. Other safety and health information on the AWS website Material or Equipment Manufacturers:

(1) Safety Data Sheets (SDS) supplied by materials manufacturers

1 See Annex A, Bibliography, for other standards and practices.